As of 6 December, 110 clinically diagnosed cases of diphtheria, including six deaths have been reported, with most cases in the Balukhali makeshift settlement (BMS), located in the larger Kutupalong–Balukhali expansion site. Other cases have been detected in Jamtoli and Thangkhali settlements. Low vaccination coverage amongst the camp population increases their vulnerability to the disease, which is particularly deadly for children. Congestion in sites, unevenly distributed health facilities and poor WASH infrastructure facilitate the spread of the disease, particularly during winter. An emergency vaccination campaign targeting 250,000 children is to begin on December 10.Difficult terrain and lack of access to some areas in expansion sites are likely tohamper health services provision. Awareness raising will be important to ensure asmany children as possible access immunisations.